1. Technical Field
The invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device with an extended life span of a lamp.
2. Related Art
A liquid crystal display device controls a light transmittance of liquid crystal cells in response to a video signal to display pictures corresponding to the video signals. A liquid crystal display device of a matrix type has a switching device arranged for every liquid crystal cell so that it is suitable for the display of a moving picture. The switching device mainly employs a thin film transistor (TFT).
The liquid crystal display device may not be a light-emitting device, so that it requires a backlight unit. A scanning backlight is a sequentially blinking lamp along a scan direction of an indicating line, as shown in FIGS. 1A to 1D. The scanning backlight applies to the liquid crystal display device to reduce a motion blurring sensed by an observer due to a maintaining characteristic of a liquid crystal material when displaying a motion picture through the liquid crystal display device. A life span of backlight lamps becomes shortened because a driving voltage applied to the lamps Ln-2, Ln-1 and Ln (see FIG. 2) repeats turning-on and turning-off by a frame period of 16.67 ms unit as shown in FIGS. 1A-1D. Accordingly, there is a need of a liquid crystal display device that may extend a life span of a backlight lamp.